Lowest production cost would be to do the whole thing in Flash. You don't really even need particularly skilled artists. If you can draw a stick figure, you can use Flash Animator. Get a few people to do the voices and you're set.

Asimov did some great short stories that were properly good sci-fi, but would work in the near future, with no special effects to speak of.

There was a great one about a child's talking robot, that told stories. But the stories were all quite samey, and eventually he got out of date and the kids abused him. It ends with the toy telling a sad story about a toy robot that wanted to entertain, but was beaten by his oppressive owners.